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New Member

Network disconnect after moving within the same VLAN

We have a 6509 by using level 3 switching as the core. Two 2912MF switches are connected to 6509 in different VLAN by trunking 2 gigabit ports each. The access layer, we are cascading 424 hub as segment and connect several segments across 2912MF switches by 100Mb F/O interface.

My problem is:

When moving a notebook or PC connection from any port of a segment to another on the same VLAN (i.e. on the same 2912MF), the network connection will not be came back. But there will be no problem for connecting in different VLAN (i.e. different 2912MF)

Does anyone have this experience? And what is the solution?

11 REPLIES
New Member

Re: Network disconnect after moving within the same VLAN

Does the PC get IP address through DHCP or static address ? If it is through DHCP, can you try using static address.

New Member

Re: Network disconnect after moving within the same VLAN

Thanks for your response.

We are using DHCP. But on my case, it is no difference for static address.

New Member

Re: Network disconnect after moving within the same VLAN

Your problem 'could' be related to a CAM refresh issue although it shouldn't since you have no problem connecting to a port on another VLAN.Try looking at the CAM table content of the switch after you move the m/c to another port.If it doesn't get updated, try refreshing it. Again...this is 'basic'....you might have a total different issue here such as a bug on the CatOS or OS issues on the m/c itself.

New Member

Re: Network disconnect after moving within the same VLAN

Hi,

Without details, this will be a hard one to solve via email.

Can you explain what you mean by "network connection will not come back"

I gues the port status is "connected" but the PC is unable to communicate with other devices. If so, look at the CAM table on the switch and ensure that the port to which the PC is connected (after moving the PC) has learnt the right MAC address.

"sho cam dynamic " where mod/port# is the port to which the PC is connected.

Try pinging a device which is connected on the same switch and is in the same vlan to avoid routing between vlans.

If you are ping a device which is on a different vlan and on Cat6k ( I assuming again ) you have supervisor1, then check the mls entry corresponding to the IP address and make sure that you see the correct MAC address, source port and the vlan#.

"sho mls entry ip dest "

Hope this helps.

Nash

New Member

Re: Network disconnect after moving within the same VLAN

The commands should be

"sh cam dynamic "

and

sh mls entry ip dest

Sorry for incomplete commands in the earlier post.

Nash

New Member

Re: Network disconnect after moving within the same VLAN

I am sure I enter the commands correctly even the first time also but it appears that this system discards anything written within the "less than" and "greater than" sign.

The commands should be "sh cam dynamic mod/port#" and "sh mls entry ip dest ipaddress"

Nash

Purple

Re: Network disconnect after moving within the same VLAN

If it's a cam aging time issue you can try issueing the clear cam dyn command , this clears cam table , then try connecting .

New Member

Re: Network disconnect after moving within the same VLAN

Thanks for your suggestion. I tried the command but this is still not working. Is there anything I miss?

New Member

Re: Network disconnect after moving within the same VLAN

Try a test using something other than the 424's.

New Member

Re: Network disconnect after moving within the same VLAN

The network connection is normal if we use some other brand name hub.

New Member

Re: Network disconnect after moving within the same VLAN

It is true that the network connection is normal when using other brand name hub e.g. 3COM. This problem has been lasted for over 6 months, but no solution provided from Cisco and our dealer and the root cause is even not yet concluded. All equipment (include 2x6509, 6x2912 and nearly hundred 424 hubs plus fiber modules) purchased are within one year. From the company point of view, I don't think it can replace hundred of hub by paying extra cost as the original equipment are just purchased. Can anyone help me and teach me how to do?

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